#define _CRT_SECURE_NO_WARNINGS 1
class Solution {
public:
	int numDistinct(string s, string t) {
		vector<vector<uint64_t>> dp(s.size() + 1, vector<uint64_t>(t.size() + 1, 0));
		for (int i = 0; i < s.size(); i++)
		{
			dp[i][0] = 1;
		}

		for (int i = 1; i <= s.size(); i++)
		{
			for (int j = 1; j <= t.size(); j++)
			{
				if (s[i - 1] == t[j - 1])
					dp[i][j] = dp[i - 1][j - 1] + dp[i - 1][j];
				else
					dp[i][j] = dp[i - 1][j];
			}
		}
		return dp[s.size()][t.size()];
	}
};